5.7 FACTORS OF SUCCESSFUL ARC WELDING
(1) CORRECT CURRENT
Welding activities or operation to be carried out depends on the nature of material. When wrong current is chosen it has effect on the choice of electrode.
Since this project on fabrication of electric arc welding machine is design to work for different metals or metal plate, therefore, for successful arc welding, correct must be used. For instance, when a current is too high for a job that low current ought to be used for, it result in damage of materials because of excessive heat, and also, when low current is adopted for big metal plate it will result in inadequate penetration of metal and there is no molten form and as a result of this no welding occurs.
(2) CHOOSING OF CORRECT ELECTRODE
The choice of correct electrode also govern successful arc welding operation. Since there are electrodes made for specific job as shown in the table earlier (Table ). In selecting the most suitable electrode, consideration must be given to the position of the weld, size of electrode, type or joint and current settings. Here are the main groups of electrode; mild steel, special alloy steel, cast iron and non-ferrous.
THE CORRECT LENGTH OF ARC
This is another factor which depends on the type of electrode used and the nature of the welding operation. For a long arc, a wide irregular bead is produced with insufficient fusion between the plate and the electrode metal. Also, insufficient heat is given out to give improper or inadequate melting of metal plate work piece when the arc product is too short. From the foregoing, correct length of arc must be achieved to give correct and successful welding.
THE CORRECT SPEED OF TRAVEL
For correct and successful welding, correct speed of electrode must be allowed. This must be slow and steady to ensure sufficient penetration without excessive build of heat. The disadvantages in excessive speed or fast speed is that the molten pool solidifies rapidly and allows the traps of impurities within which may result in pitting and brittle welds, while slow speed produces a high and wide bead.
5.8 MAINTENANCE
All machinery in engineering field requires periodic maintenance in order to avoid total break down of equipment or in other word, cause hazard to the user especially when the machine is using electric energy as a source of power. Though in the case of this welding machine it is made simple enough to maintain yet some routine checks can not at all be made unnecessary.
The routine checks involve (checks before use and maintenance)
Before Use Checks
-Check the mains input and welding cable for signs of deterioration or damage
-Check that the condition of the electrode holder is in good electrical contact with the electrode.
-Check that the welding lead and return lead terminal are both electrically continuous and mechanically sound
-Check to ensure that the housing or container did not rest on the fan blade i.e. the fan blade as free movement without touching any part of the housing for cooling of the winding to avoid overheating.
Routine Maintenance: This is carried out periodically to check the transformer component inside the welding machine. Since this project is designed to be installed with air-cooling system dust must not be allowed to stick to the transformer as it may cause the machine to be overheated inspection of the weld terminals which must be clean and lighten, then service the air filter and the cooling system ‘air-cooled which is fan blade’ then check the fan clearance from the housing for smooth running. After the transformer is removed the entire component is blow out or vacuum both the
transformer and inner part of the housing.
5.9 THE SAFETY PRECAUTIONS
(i) Hazardous Conditions: High temperature will overheat the machine and very cold weather will make some types of electrical insulation brittle. Exposure to abrasive, dust will shorten the life span. Also, striking an arc in area with a potentially abnormal vibration or mechanical shock can distort operation and harmful to the operator.
(ii) Electrical Hazard: Electrical shock is the most critical hazard in arc welding that is why you have to be extra-ordinary careful with a power source when you are and you are not welding. Also, the machine should be connected to a power supply only of the type specify in the operating instruction/manual of the machine.
(iii) Always Ground Your Equipment: The first thing to be done when a job is set up to work on before turning on the power source, attach the ground cable to the work piece with the ground clamp. That will complete the electric circuit when the power source turn ON and when the machine is turn ON. The circuit is closed by striking an arc with an electrode. Also, the metal machine should be grounded as well.
(iv) Machine Duty Cycles: Standard arc welding machine are designed and built to carry out a current at rated duty cycle. The duty cycle is the amount of time a welding machine can operate is rated current without overheating and is usually measured over rated current on the name – plate of welding machine.
(v) Power Supply Wiring: Before you begin to work with any welding machine you should make sure that the power supply cable is properly connected to its right rated power supply lines. And it should be large enough to carry its rated as special in its name-plate.
(vi) Electrode Holders: Electrical holders are used for champing stick electrodes and hold them while you weld. Only use electrode holders specifically designed for a particular welding. The handle parts of the electrode holder must be insulated to withstand the maximum voltage being used.
(vii) Non-Used Period: The power cord of the machine should be unplugged from the power socket when the machine is not in use for a period of time.
(vii) Read Instructions: All the safety and operating instruction of the machine should be read properly before the appliance is operated. And these instruction should be trained for future.
(viii) Eye Protection: Beside the intense light, most welding process produce invisible ultra-violet rays that can damage your eyes or burn your skin. That is why it is important to wear dark glass that screens out all but enough list to see the arc, wearing of helmets also protect your whole face from being sun burn.
(x) Safe Maintenance: Here are few rules for safety operation and monitoring your welding equipment. Although this unit requires less attention and service due to its simplicity in design and instruction. Some routine maintenance and before use checks arc important and necessary. This is to ensure that the equipment is fully in a serviceable and reliable condition.
TESTING OF THE FABRICATED ELECTRIC ARC WELDING MACHINE
TESTING OF AN ELECTRIC ARC WELDING MACHINE
The project was tested immediately after the fabrication. In other to amend or correct, but it was noted that project worked perfectly land the transformer rating is okay and ready for used.
